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The coded spectrometer, a relatively new instrument, has the advantage of high signal-to-noise ratio, giving it great application potential. We report the optical design of a space-based visible coded spectrometer based on curved prism dispersion (SVCS-CPD) and further explore the design and analysis of its support structure. A static simulation and modal analysis, sinusoidal vibration mechanical analysis, and random vibration mechanical analysis were performed to demonstrate the excellent mechanical and thermal stability of the support structure. To realize rapid assembly and integration of the off-axis optical system, a point source microscope and three-coordinate measuring machines were employed. In addition, tests of optical design parameters and outdoor push-scan imaging were conducted to validate the high imaging performance of the SVCS-CPD. The results showed that the modulation transfer functions of the SVCS-CPD in the central and marginal fields of view were 0.61 at 31.25 line pairs/mm and 0.53 at 31.25 line pairs/mm, respectively. In addition, the spectral smile and spectral keystone were < 0.3 pixels. The development of the SVCS-CPD can provide a useful reference for similar spaceborne dispersion spectrometers. [ABSTRACT FROM AUTHOR]

Cryogenic environments benefit ion trapping experiments by offering lower motional heating rates, collision energies, and an ultrahigh vacuum (UHV) environment for maintaining long ion chains for extended periods of time. Mechanical vibrations caused by compressors in closed-cycle cryostats can introduce relative motion between the ion and the wavefronts of lasers used to manipulate the ions. Here, we present a novel ion trapping system where a commercial low-vibration closed-cycle cryostat is used in a custom monolithic enclosure. We measure mechanical vibrations of the sample stage using an optical interferometer, and observe a root-mean-square relative displacement of 2.4 nm and a peak-to-peak displacement of 17 nm between free-space beams and the trapping location. We packaged a surface ion trap in a cryopackage assembly that enables easy handling while creating a UHV environment for the ions. The trap cryopackage contains activated carbon getter material for enhanced sorption pumping near the trapping location, and source material for ablation loading. Using $^{171}$Yb$^{+}$ as our ion, we estimate the operating pressure of the trap as a function of package temperature using phase transitions of zig-zag ion chains as a probe. We measured the radial mode heating rate of a single ion to be 13 quanta/s on average. The Ramsey coherence measurements yield 330-ms coherence time for counter-propagating Raman carrier transitions using a 355-nm mode-locked pulse laser, demonstrating the high optical stability.

Featured Application: Applications of polygon mirror-based scanning heads include laser scanning, 2D and 3D printing, laser manufacturing, imaging, optical metrology, and Remote Sensing. Polygon Mirror (PM)-based scanning heads are one of the fastest and most versatile optomechanical laser scanners. The aim of this work is to develop a multi-parameter opto-mechanical analysis of PMs, from which to extract rules-of-thumbs for the design of such systems. The characteristic functions and parameters of PMs scanning heads are deduced and studied, considering their constructive and functional parameters. Optical aspects related to the kinematics of emergent laser beams (and of corresponding laser spots on a scanned plane or objective lens) are investigated. The PM analysis (which implies a larger number of parameters) is confronted with the corresponding, but less complex aspects of Galvanometer Scanners (GSs). The issue of the non-linearity of the scanning functions of both PMs and GSs (and, consequently, of their variable scanning velocities) is approached, as well as characteristic angles, the angular and linear Field-of-View (FOV), and the duty cycle. A device with two supplemental mirrors is proposed and designed to increase the distance between the GS or PM and the scanned plane or lens to linearize the scanning function (and thus to achieve an approximately constant scanning velocity). These optical aspects are completed with Finite Element Analyses (FEA) of fast rotational PMs, to assess their structural integrity issues. The study is concluded with an optomechanical design scheme of PM-based scanning heads, which unites optical and mechanical aspects—to allow for a more comprehensive approach of possible issues of such scanners. Such a scheme can be applied to other types of optomechanical scanners, with mirrors or refractive elements, as well. [ABSTRACT FROM AUTHOR]

Surface aberrations of transport mirrors within Inertial Confinement Fusion laser facility have significant impacts on system's optical and physical performances. Mounting design of transport mirrors is challenging for the critical specifications of mirror surface aberration under extreme operation environment. This paper presents a novel and general flexure mounting method and structure for transport mirrors with various-axis towards gravity to minimize the mirror surface aberration. Key techniques involved in mirror mounting design, including theoretical modeling, numerical optimization, optomechanical structure design and analysis, and optical testing are explored. The relationship between mirror surface aberration and its use angle θ subject to gravity is clarified using thin elastic plate theory. The mounting configuration is parametrically optimized with a more comprehensive mathematical model. Optomechanical structure design and analysis of the flexure mirror mount are detailed and accomplished. The performance of the proposed mount is experimentally validated by interferometric measurements. Experimental results indicate that the designed mirror mount potentially provides the transport mirrors (with 45° ≤ θ ≤ 90° and no screw pretension) a peak-to-valley aberration level about λ/3 (λ = 632.8 nm) of the total aberration and ∼λ/4 of the residual aberration, respectively. The proposed mounting method and structure provide a feasible and promising method and technique scheme to minimize the transport mirror surface aberrations for the next generation Inertial Confinement Fusion laser facility. The paper work also represents a design effort and a beneficial attempt for analyzing and minimizing gravity aberration for large-aperture, various-axis, and rectangular flat mirrors. [Display omitted] • Effects of gravity on surface aberrations of various-axis transport mirrors are analyzed. • A novel and general mounting method for various-axis transport mirrors is proposed. • A comprehensive optimization for the mounting configuration is mathematically established and accomplished. • An adjustable transport mirror mount, using a novel flexure beam, is designed and numerically analyzed. • Numerical and experimental results show that the proposed mounting method and structure is feasible. [ABSTRACT FROM AUTHOR]

• Lens mounting with six contacts glue pad produce the optimum configuration in opto-mechanical assembly. • Non-linear properties of glue pad affect the Von-Mises stresses distributions. • High number of glue contact caused a bigger problem of lens distortion. Optomechanical systems are very complex requiring a high degree of accuracy. The carrier structure of an optical system is required to maintain the position of the optical components with respect to each other within the design tolerances. The most common loads on optical systems are self-weight, due to gravity orientations, and temperature ranges, due to exposure to rapidly changing temperatures from very cold to very hot and during launch. The fixing should ensure mechanical stability and thus accurate positioning in various gravity orientations. In order to ensure reliability during a space flight mission, the optomechanical engineer must understand the requirements of the space flight environment as well as the physics of failure of the optical components themselves; this can minimize the risks of on-orbit failure. This paper focuses on the optomechanical optimal design lens mounting using glue pads bonding. The main idea of this research study is to obtain an optimal choice of the position of the glue to fix the lenses on the barrel in such a way that we obtain a configuration of the optical assembly performance with less stress. In this paper, an investigation was performed using several methods including (thermo-elastic analysis, the margin of safety and lens distortion analysis). The results show that the position with six contacts glue pads is the best configuration compared to other configurations. This solution can be very helpful for decision-makers and optical engineers during the development phases of space optomechanical systems. [ABSTRACT FROM AUTHOR]

Laser beam distribution requires complex opto-mechanical system allowing safe and precise delivery of different laser beams from hall laboratories to experimental workstations developed within the HiLASE project of the IOP in the Czech Republic. The unique nature of new generation of HiLASE high energy diode-pumped solid state laser systems with high repetition rates requires advanced design approach. We use modular approach that allows gradual modification and flexible change of the distribution layout according to current laboratory needs as well as customization of individual branches including their optical, mechanical and electronic equipment. The distribution system performance excels with high pointing stability and low vibration transmission. [ABSTRACT FROM AUTHOR]

Abstract This study aims to identify numerical analysis methods for the reliability prediction of rotating mirror(RM) strength at the early-stage design. A mathematical model for the strength reliability analysis of RM is established based on the Monte Carlo method, small-sample theory, and reliability principle. Numerical analysis on the strength reliability of RM is conducted, and the results are experimentally verified according to small-sample theory. The spearman rank order correlation coefficients between structure parameters and the maximum stress is the circumradius of mirror body, and that of the material variable is the elastic modulus of high-strength aluminum alloy(Al). The skewness and kurtosis values of maximum stress and strain are all positive. Calculated statistical results obey normal distribution and are right skewed. At 95% confidence level, the strength reliability of the RM with a design speed of 70,000 rpm is 0.999. This finding shows that the strength reliability of the RM meets the required design in ideal state. No failure of RMs occurs among strength reliability experiment, proving the validity of the numerical model. This model provides an economic, feasible, and effective method for estimating the strength reliability of RM. [ABSTRACT FROM AUTHOR]

Spray drift is one of the main sources of pesticide contamination. For this reason, an accurate understanding of this phenomenon is necessary in order to limit its effects. Nowadays, spray drift is usually studied by using in situ collectors which only allow time-integrated sampling of specific points of the pesticide clouds. Previous research has demonstrated that the light detection and ranging (lidar) technique can be an alternative for spray drift monitoring. This technique enables remote measurement of pesticide clouds with high temporal and distance resolution. Despite these advantages, the fact that no lidar instrument suitable for such an application is presently available has appreciably limited its practical use. This work presents the first eye-safe lidar system specifically designed for the monitoring of pesticide clouds. Parameter design of this system is carried out via signal-to-noise ratio simulations. The instrument is based on a 3-mJ pulse-energy erbium-doped glass laser, an 80-mm diameter telescope, an APD optoelectronic receiver and optomechanically adjustable components. In first test measurements, the lidar system has been able to measure a topographic target located over 2 km away. The instrument has also been used in spray drift studies, demonstrating its capability to monitor the temporal and distance evolution of several pesticide clouds emitted by air-assisted sprayers at distances between 50 and 100 m.

We theoretically and numerically investigated the modal properties of three different kinds of cross-section rotating mirrors. At the same facet size, the fundamental frequency of equilateral-triangle cross-section rotating mirror (ET-RM) was 8725.4 Hz, which was 1.81 times and 4.60 times higher than that of equilateral-square and equilateral-hexagonal rotating mirrors. The displacement response curves of the three kinds rotating mirrors show that the amplitude of the first peak is further larger than the second one. The first bending modal of rotating mirror is the main reason of the damage for rotating mirrors. The maximum working speed of ET-RM with face size of 17.32 mm × 36 mm is 44,400 rpm. That of the other two kinds of rotating mirror are 37,800 rpm and 27,000 rpm respectively. The equilateral-triangle cross-section as an ideal structure of rotating mirror for ultra-high-speed cameras based on the dynamic properties. [ABSTRACT FROM AUTHOR]

We theoretically and numerically studied the properties of a high-strength magnesium alloy rotating mirror (Mg-RM) as a novel potential candidate for an ultra-high speed camera. The maximum lateral deformation of the Mg-RM was reduced to 0.92 times that of a high-strength aluminium alloy rotating mirror (Al-RM) at a rotating speed of 5 × 10 5 revolutions per minute (rpm). Meanwhile, compared to the Al-RM, the limit edge linear velocity of the Mg-RM was improved by 1.11 times, indicating that the limit time resolution could be improved by 11% when used for an ultra-high speed camera. According to our theoretical and numerical investigations, the remarkable properties of the Mg-RM, indicate that the high-strength magnesium alloy is another ideal and novel RM material for ultra-high speed cameras. [ABSTRACT FROM AUTHOR]

Influence of radiation force of a high-energy laser beam on the second harmonic generation (SHG) efficiency through stress within a mounted potassium dihydrogen phosphate (KDP) crystal is studied, as well as an active method of improving the SHG efficiency by controlling the stress is proposed. At first, the model for studying the influence of the radiation force on the SHG efficiency is established, where the radiation force is theoretically analyzed, the stress caused by the radiation force is theoretically analyzed and numerically calculated using the finite-element method, and the influence of the stress on the SHG efficiency is theoretically analyzed. Then, a method of improving the SHG efficiency by controlling the stress through adjusting the structural parameters of the mounting set of the KDP crystal is examined. It demonstrates that the radiation force causes stress within the KDP crystal and further militates against the SHG efficiency; however, the SHG efficiency could be improved by controlling the stress through adjusting the structural parameters of the mounting set of the KDP crystal. [ABSTRACT FROM AUTHOR]

Surface control and phase matching of large laser conversion optics are urgent requirements and huge challenges in high-power solid-state laser facilities. A self-adaptive, nanocompensating mounting configuration of a large aperture potassium dihydrogen phosphate (KDP) frequency doubler is proposed based on a lever-type surface correction mechanism. A mechanical, numerical, and optical model is developed and employed to evaluate comprehensive performance of this mounting method. The results validate the method’s advantages of surface adjustment and phase matching improvement. In addition, the optimal value of the modulation force is figured out through a series of simulations and calculations. [ABSTRACT FROM AUTHOR]

This paper relates to the improvement of conventional surgical stereo microscopy via the application of digital recording devices and adaptive optics. The research is aimed at improving the working conditions of the surgeon during the operation, such that free head movement is possible. The depth clues known from conventional stereo microscopy in interaction with the human eye's functionality, such as convergence, disparity, angular elevation, parallax, and accommodation, are implemented in a digital recording system via adaptive optomechanical components. Two laterally moving pupil apertures have been used mimicking the digital implementation of the eye's vergence and head motion. The natural eye's accommodation is mimicked via the application of a tunable lens. Additionally, another system has been built, which enables tracking the surgeon's eye pupil through a digital displaying stereoscopic microscope to supply the necessary information for steering the recording system. The optomechanical design and experimental results for both systems, digital recording stereoscopic microscope and pupil tracking system, are shown. [ABSTRACT FROM AUTHOR]

We present the design concept and validation of a cryogenic lens mount for a noncemented doublet for the near-infrared diffraction limited instrument FRIDA. The design uses an autocentering mount that maintains the relative alignment of the lenses, acting against any displacement that may be induced by external forces by automatically returning the lenses to their nominal positions. Autocentering techniques have been used for instruments at room temperature with relatively relaxed image quality requirements. We present in detail its application to a mount for a cryogenic instrument working at the diffraction limit. The design has been tested on the collimator of FRIDA, a noncemented doublet of CaF2 and S-FTM16. We describe the alignment requirements of the system, and we show the calculations that ensure that the lenses will suffer both appropriate stresses and temperature differences. We present the experimental validation of a prototype, demonstrating that the design delivers an excellent performance without inducing unnecessary stresses on the optical components, provided that the lenses are previously aligned with very high precision [ABSTRACT FROM AUTHOR]

It has long been recognized in the design of micromirror-based optical systems that balancing static flatness of the mirror surface through structural design with the system's mechanical dynamic response is challenging. Although a variety of mass reduction approaches have been presented in the literature to address this performance trade, there has been little quantifiable comparison reported. In this work, different mass reduction approaches, some unique to the work, are quantifiably compared with solid plate thinning in both curvature and mass using commercial finite element simulation of a specific square silicon-on-insulator-based micromirror geometry. Other important considerations for micromirror surfaces, including surface profile and smoothness, are also discussed. Fabrication of one of these geometries, a two-dimensional tessellated square pattern, was performed in the presence of a 400-µm-tall central post structure using a simple single mask process. Limited experimental curvature measurements of fabricated samples are shown to correspond well with properly characterized simulation results and indicate ~67% improvement in radius of curvature in comparison to a solid plate design of equivalent mass. [ABSTRACT FROM AUTHOR]

The Full Disk Telescope is part of the Polarimetric Helioseismic Instrument on board the future Solar Orbiter ESA/NASA mission. It will provide full-disk measurements of the photospheric magnetic field vector and line-of-sight velocity, as well as the continuum intensity in the visible wavelength range. Along this mission, it is expected that thermal drifts will induce image focus displacements. Consequently, providing an autofocus system is mandatory to prevent image degradation. The refocusing system is based on an autonomous image contrast analysis and it allows for a lens displacement in order to locate the best focus position. The figure of merit chosen for the image quality evaluation is presented. The influences of attitude instability and mechanical uncertainties are considered in a refocusing process simulation. In addition, an engineering model of the mechanism is tested at flight operating conditions. To check its performance, an optical interrogation system is set up. Determination of accuracy and repeatability of the mechanism positioning is experimentally evaluated and discussed according to the ISO standard. The results show that the proposed refocusing system is sufficiently robust against the expected image shifts and mechanical instabilities. [ABSTRACT FROM AUTHOR]

Nanoelectromechanical systems (NEMS) design for active resonance frequency tuning of plasmonics optical filter is proposed and discussed. The design is based on controlling the relative position between two stubs in a metal-insulator-metal plasmonics waveguide using NEMS technology. The analysis of the optical design as well as the mechanical design is performed. Finally, a reasonable fabrication process of the device is proposed. For the suggested mechanical design parameters, the optical resonance wavelength can be tuned from 1.45 to 1.65 µm using 7VDC actuation voltage. [ABSTRACT FROM AUTHOR]

Spray drift is one of the main sources of pesticide contamination. For this reason, an accurate understanding of this phenomenon is necessary in order to limit its effects. Nowadays, spray drift is usually studied by using in situ collectors which only allow time-integrated sampling of specific points of the pesticide clouds. Previous research has demonstrated that the light detection and ranging (lidar) technique can be an alternative for spray drift monitoring. This technique enables remote measurement of pesticide clouds with high temporal and distance resolution. Despite these advantages, the fact that no lidar instrument suitable for such an application is presently available has appreciably limited its practical use. This work presents the first eye-safe lidar system specifically designed for the monitoring of pesticide clouds. Parameter design of this system is carried out via signal-to-noise ratio simulations. The instrument is based on a 3-mJ pulse-energy erbium-doped glass laser, an 80-mm diameter telescope, an APD optoelectronic receiver and optomechanically adjustable components. In first test measurements, the lidar system has been able to measure a topographic target located over 2 km away. The instrument has also been used in spray drift studies, demonstrating its capability to monitor the temporal and distance evolution of several pesticide clouds emitted by air-assisted sprayers at distances between 50 and 100 m. [ABSTRACT FROM AUTHOR]